This is good for protoboeuf and other binary parsing

Inspired by 42ba82424d908c290a4a34ced8853f0a403b734b, I looked for other
occurrences of "the the".

* ZJIT: Fix disasm tests on release build

* Rename string() to hexdump()

Save a couple instructions to load a small negative constant into a
register. In fact MOVN is speced to alias as `mov` in the official
disassembly.